/*
 * Copyright 2000-2012 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.util.keyFMap;

import com.intellij.openapi.util.Key;
import org.jetbrains.annotations.NotNull;

final class OneElementFMap implements KeyFMap {
    private final Key myKey;
    private final Object myValue;

    public <V> OneElementFMap(@NotNull Key<V> key, @NotNull V value) {
        myKey = key;
        myValue = value;
    }

    @NotNull
    @Override
    public <V> KeyFMap plus(@NotNull Key<V> key, @NotNull V value) {
        if (myKey == key) {
            return value == myValue ? this : new OneElementFMap(key, value);
        }
        return new PairElementsFMap(myKey, myValue, key, value);
    }

    @NotNull
    @Override
    public KeyFMap minus(@NotNull Key<?> key) {
        return key == myKey ? KeyFMap.EMPTY_MAP : this;
    }

    @Override
    public <V> V get(@NotNull Key<V> key) {
        //noinspection unchecked
        return myKey == key ? (V) myValue : null;
    }

    @Override
    public int size() {
        return 1;
    }

    @NotNull
    @Override
    public Key[] getKeys() {
        return new Key[]{myKey};
    }

    @Override
    public String toString() {
        return "{" + myKey + "=" + myValue + "}";
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public int getValueIdentityHashCode() {
        return myKey.hashCode() * 31 + System.identityHashCode(myValue);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof OneElementFMap)) return false;

        OneElementFMap map = (OneElementFMap) o;
        return myKey == map.myKey && myValue.equals(map.myValue);
    }

    @Override
    public boolean equalsByReference(KeyFMap o) {
        if (this == o) return true;
        if (!(o instanceof OneElementFMap)) return false;

        OneElementFMap map = (OneElementFMap) o;
        return myKey == map.myKey && myValue == map.myValue;
    }

    @Override
    public int hashCode() {
        return myKey.hashCode() ^ myValue.hashCode();
    }
}
